416 SUBMARINE CABLE LAYING AND REPAIRING. 



For the remaining pairs the correction is worked out as 



follows : — 



39.5 

 Eatio of testing currents (n) = =2"47. 



By the Table, M = 0-46 3. 



nc= - — - =^6"58 m/amps. 

 o X 1j 



6=1,417 m/ volts. 

 Therefore, the correction 



±M=-h^ll2i:^ = 100 ohms. 

 nc 6-68 



These corrections are additive because the earth currents 

 were opposite in direction to the standard cell current. 

 Another set, taken on the same break, was as follows : — 

 Constant.— Same as before for 1,460 millivolts, 268° to Left. 

 Earth Current. — Before commencing test, 430° to the Right. 



1 minute after test, 600° „ ,, 



Earth current voltages corresponding to these deflections are 

 ■respectively : — 



1,460x430 



268 



= 2,343 m/volts 



and l,460x600 ^3^,,o ^, 



Hob 



Balances — The balance B with the high current is taken 



first. 



37 cells ^^"^ 

 16 .. 



.c=6,76S 6,631 6.791 

 Mean of three sets=6,730 ohms. 

 Actual distance of breaks 6,744 ohms from Sierra Leone. 



